scholarly journals Effect of Curing Temperature on the Properties of Cementitious Waste Forms

1989 ◽  
Vol 176 ◽  
Author(s):  
Ryan O. Lokken ◽  
John W. Shade ◽  
Paul F. C. Martin
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Liquid Waste ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Curing Time ◽  
Low Level ◽  
Waste Forms ◽  
Liquid Wastes ◽  
Time Periods

ABSTRACTCurrent plans for disposing various low-level radioactive and/or hazardous liquid wastes include solidification of the waste using cementitious materials. One process, known as grouting, involves mixing liquid wastes with a blend of cementitious materials and pumping the resultant slurry to lined, underground concrete vaults. As the grout slurry begins to solidify and harden, the temperature within the grout increases due to exothermic hydration reactions. Depending on the the particular grout composition and on the disposal conditions, the grout may be exposed to temperatures of around 90°C for extended time periods. Studies are being conducted to determine the effects of high-temperature curing on selected properties of grouts prepared with a simulated low-level liquid waste. Grout samples cured at temperatures up to 950C in the laboratory absorbed water during curing. The resultant leach resistance and compressive strength of these grouts decreased with increases in curing temperature and curing time.

Efficiency of Sulfoaluminate Cement for Solidification of Simulated Radioactive Borate Liquid Waste

2010 ◽  
Author(s):  
Qina Sun ◽  
Junfeng Li ◽  
Jianlong Wang ◽  
Shixi Ouyang ◽  
Qiang Li ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Impact Resistance ◽  
Liquid Waste ◽  
Radioactive Isotopes ◽  
National Standard ◽  
Leaching Test ◽  
Testing Procedures ◽  
Waste Forms ◽  
Solidified Waste ◽  
Liquid Wastes

To investigate the solidification efficiency of sulfoaluminate cement (SAC) and to provide more information for formula optimization, SAC blending zeolite, accelerator and Dura fiber was used as matrix materials for solidification of simulated radioactive borate liquid waste. The simulated radioactive borate liquid waste was prepared with boric acid and sodium hydroxide using drinking water. The performances of solidified waste forms were evaluated mainly basing on matrix compressive strength and leachability. The 28d compressive strength of the solidified waste forms were tested according to Chinese National Standard GB 14569.1-1993, and experiments on water/freezing/irradiation/impact resistance were also carried out. Nuclides Sr, Cs and Co were substituted by their non-radioactive isotopes respectively in leachability test, and the testing procedures were consistent with Chinese National Standard GB 7023-1986. Experimental results showed that it was feasible to solidify borated liquid wastes with SAC. The 28d compressive strength was 13.9MPa, nearly twice of the standard in GB 14569.1-1993. Strength losses in water/freezing/irradiation/impact resistance tests met the demands of GB 14569.1-1993 well. In the leaching test, the 42d leaching rates were 3.39×10−5 cm/d, 4.45×10−5 cm/d and 4.07×10−7 cm/d for Sr2+, Cs+ and Co2+ respectively, much lower than GB 14569.1-1993 limits. Results of leaching test also showed that the leaching mechanism of Co2+ was different from that of Sr2+ and Cs+.

scholarly journals Synthesis of Geopolymer from Inorganic Construction Waste

2013 ◽  
Vol 30 ◽  
pp. 45-51 ◽  
Author(s):  
Arbind Pathak ◽  
Vinay Kumar Jha
Keyword(s):  
Compressive Strength ◽  
Coal Fly Ash ◽  
Chemical Society ◽  
Raw Material ◽  
Curing Temperature ◽  
Alkali Concentration ◽  
Curing Time ◽  
Mass Ratio ◽  
Construction Waste ◽  
Alumino Silicate

Recently, the demolition of old houses and the construction of new buildings in Kathmandu valley are in the peak which in turn generates a huge amount of construction waste. There are two major types of construction wastes which are burden for disposal namely cement-sand-waste (CSW) and the coal fly ash (CFA). These construction wastes are rich source of alumino-silicate and thus used as raw material for the synthesis of geopolymer in this study. Geopolymers have been synthesized from CSW and CFA using NaOH-KOH and Na2SiO3 as activators. Some parameters like alkali concentration, amount of Na2SiO3 and curing time have been varied in order to improve the quality of geopolymeric product. The geopolymerization process has been carried out using 3-8M KOH/NaOH solutions, Na2SiO3 to CFA and CSW mass ratio of 0.25-2.00 and curing time variation from 5-28 days. The curing temperature was fixed at 40ºC in all the cases. 6M NaOH and 7M KOH solutions were found appropriate alkali concentrations while the ratio of sodium silicate to CSW and CFA of 0.5 and 1.75 respectively were found suitable mass ratio for the process of geopolymer synthesis. The maximum compressive strength of only 7.3 MPa after 15 days curing time with CSW raw material was achieved while with CFA, the compressive strength was found to be 41.9 MPa with increasing the curing time up to 28 days.DOI: http://dx.doi.org/10.3126/jncs.v30i0.9334Journal of Nepal Chemical Society Vol. 30, 2012 Page:  45-51 Uploaded date: 12/16/2013    

Effects of Microstructure on Fracture Behavior of Hardened Cement Paste

1994 ◽  
Vol 370 ◽  
Author(s):  
Asif Ahmed ◽  
Leslie Struble
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Paste ◽  
Fracture Behavior ◽  
Curing Temperature ◽  
Hardened Cement ◽  
Curing Time ◽  
Hardened Cement Paste ◽  
Fracture Parameters ◽  
Initial Hypothesis

AbstractMechanical properties of any material, including hardened cement paste, are assumed to be controlled by its microstructure. An attempt has been made here to establish a link between bulk fracture parameters of hardened cement paste and its microstructure. Paste microstructure has been varied by changing the initial w/c ratio, curing time and curing temperature, and by addition of chemicals to change the calcium hydroxide morphology. It has been found that, like compressive strength, fracture parameters depend directly on porosity. Contrary to our initial hypothesis, CH morphology was found to have no effect on the fracture parameters.

Permeability of Expansive Soils Modified/Stabilized with lime (Review Paper)

2021 ◽  
Vol 14 (2) ◽  
pp. 129-140
Author(s):  
Muwafaq Awad ◽  
Ibrahim Al-Kiki ◽  
Amina Khalil
Keyword(s):  
Expansive Soils ◽  
Expansive Soil ◽  
Pozzolanic Reaction ◽  
Curing Temperature ◽  
Curing Time ◽  
Short Term ◽  
Coefficient Of Permeability ◽  
Review Study ◽  
Time Periods

The aim of this paper was to review the mechanism of the expansive soil-lime reactions: short term and long-term reactions in both lime modification and lime stabilization. The focus of the study was the effect of curing time for a certain centigrade 25C curing temperature in both lime modification / stabilization-expansive soils on the coefficient of permeability. Peer reviewed articles published between 2000- and 2019 were collected and relevant data were extracted. Results of this review study showed that the coefficient of permeability of expansive soils modified with lime increased during the first 7 days of curing time at curing temperature 25C and it remains constant or slightly decreased for longer curing time periods. However, for expansive soils stabilized with lime, it was found that the coefficient of permeability increased during the first 7-day curing time at curing temperature 25C, then decreased during the longer curing time periods (pozzolanic reaction). It is also noted that even though the coefficient of permeability decreased during pozzolanic reaction, it remains higher than that of the untreated soils

Development and Change of Compressive Strength for Class G Oil Well Cement under High Temperature

2014 ◽  
Vol 941-944 ◽  
pp. 1441-1444 ◽  
Author(s):  
Jing Fu Zhang ◽  
Kai Liu ◽  
Rui Xue Hou ◽  
Bo Wang ◽  
Jin Long Yang
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Initial Period ◽  
Strength Development ◽  
Oil Well ◽  
Curing Time ◽  
Cement Slurry ◽  
Critical Temperatures ◽  
Oil Well Cement ◽  
Well Cement

The compressive strength of oil well cement would be damaged by high temperature in deep oil wells, which was caused by the obvious change of the components and microstructure of cement hydration products. The adaptability of common oil well cement for cementing under higher temperatures was confined by above reasons. Characteristics of development and change of compressive strength of Class G oil well cement were studied under different temperatures by using Static Gel Strength Analyzer and High Temperature-High Pressure curing chamber. The influence law of temperature and silica sands on compressive strength was analyzed. The results showed that the critical temperatures at which the compressive strength begun to decline were about 110°C and 150°C respectively; The compressive strength increased with curing time during the initial period and would reduced after it reached a certain value when temperature exceeded 110°C; For cement with silica sands, the compressive strength development trend was in the shape of two-stage form with increase of curing time within the range of 110~150°C, but for 160~200°C temperature range the development form was in the shape of single stage; The reasonable amounts of silica sands which would be added to cement slurry to enhance the compressive strength of hardening paste were determined to be 30%~40%.

scholarly journals Factors Affecting Alkali Activation of Laterite Acid Leaching Residues

Environments ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 4
Author(s):  
Konstantinos Komnitsas ◽  
Georgios Bartzas ◽  
Vasiliki Karmali ◽  
Evangelos Petrakis
Keyword(s):  
Compressive Strength ◽  
Environmental Sustainability ◽  
Structural Integrity ◽  
Acid Leaching ◽  
Sodium Silicate Solution ◽  
Curing Temperature ◽  
Alkali Activation ◽  
Curing Time ◽  
Synthesis Conditions ◽  
Alkali Activated

In this experimental study, the alkali activation of acid leaching residues using a mixture of sodium hydroxide (NaOH) and alkaline sodium silicate solution (Na2SiO3) as activators is investigated. The residues were also calcined at 800 and 1000 °C for 2 h or mixed with metakaolin (MK) in order to increase their reactivity. The effect of several parameters, namely the H2O/Na2O and SiO2/Na2O ratios present in the activating solution, the pre–curing time (4–24 h), the curing temperature (40–80 °C), the curing time (24 or 48 h), and the ageing period (7–28 days) on the properties of the produced alkali activated materials (AAMs), including compressive strength, porosity, water absorption, and density, was explored. Analytical techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and elemental mapping analysis were used for the identification of the morphology and structure of the final products. The experimental results show that the laterite acid leaching residues cannot be alkali activated in an unaltered state, and the compressive strength of the produced AAMs barely reaches 1.4 MPa, while the mixing of the residues with 10 wt% metakaolin results in noticeably higher compressive strength (41 MPa). Moreover, the calcination of residues at 800 and 1000 °C has practically no beneficial effect on alkali activation. Alkali activated materials produced under the optimum synthesis conditions were subjected to high temperature firing for 2 h and immersed in distilled water or acidic solution (1 mol L−1 HCl) for 7 and 30 days in order to assess their structural integrity under different environmental conditions. This study explores the potential of alkali activation of laterite leaching residues amended with the addition of metakaolin for the production of AAMS that can be used as binders or in several construction applications in order to enable their valorization and also improve the environmental sustainability of the metallurgical sector.

scholarly journals The influence of curing temperature, plastic additives and polypropylene fibers on the mechanical behaviour of cementitious materials

2020 ◽  
Vol 150 ◽  
pp. 02012
Author(s):  
Mohammed Aqil ◽  
Lahcen Bahi ◽  
Latifa Ouadif ◽  
Siham Belhaj ◽  
Raounak Edderkaoui
Keyword(s):  
Compressive Strength ◽  
Mechanical Behaviour ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Polypropylene Fibers ◽  
Hydration Kinetics ◽  
Degree Of Hydration ◽  
History Of ◽  
Kinetics Of

An experimental company was carried out to better understand the influence of curing temperature on the mechanical behaviour of cementitious materials, particularly compressive strength, the study focused on two types of mortars, the first containing polypropylene fibers while the second contains a proportion of PVC-type plastic grains from industrial waste, the hydration kinetics of the different components of the formulated mortar has been characterized by the isothermal calorimetric test, thus a history of the hydration degrees has been established, Afterwards, an attempt was made to correlate the compressive strength with the evolution of the degree of hydration for the different formulations, based on the results obtained, it is clearly observable that the compressive strength evolves with the degree of hydration and that the specimen containing the polypropylene fibers has the best mechanical performance with respect to compression.

Effect of Curing Conditions on the Mechanical Properties of Fly Ash-Based Geopolymer without Sodium Silicate Solution

2014 ◽  
Vol 699 ◽  
pp. 15-19 ◽  
Author(s):  
Rosniza Hanim Abdul Rahim ◽  
Khairun Azizi Azizli ◽  
Zakaria Man ◽  
Muhd Fadhil Nuruddin
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Room Temperature ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Curing Temperature ◽  
Curing Time

Geopolymer is associated with the alkali activation of materials rich in Si and Al, and alkali activator such as sodium hydroxide is used for the dissolution of raw material with the addition of sodium silicate solution to increase the dissolution process. However, the trend of strength development of geopolymer using sodium hydroxide alone is not well established. This paper presents an evaluation on compressive strength of fly ash–based geopolymer by varying curing time with respect to different curing temperature using sodium hydroxide as the only activator. The samples were cured at room temperature and at an elevated temperature (60°C). Further analysis on the microstructure of geopolymer products cured at 60°C was carried out using Field Emission Scanning Microscopy (FESEM). It can be observed that the compressive strength increased as the curing time increased when cured at room temperature; whereas at elevated temperature, the strength increased up to a maximum 65.28 MPa at 14 days but gradually decreased at longer curing time. Better compressive strength can be obtained when the geopolymer was cured at an elevated temperature compared to curing at room temperature.

Stabilization of Sulfate-Containing Soil by Cementitious Mixtures Mechanical Properties

2003 ◽  
Vol 1837 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Lan Wang ◽  
Amitava Roy ◽  
Roger K. Seals ◽  
John B. Metcalf
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Type I ◽  
Size Fractions ◽  
Granulated Blast Furnace Slag ◽  
Local Parish ◽  
Stabilized Soil ◽  
North Louisiana

Winn Rock (CaSO4) gravel from a quarry in Winn Parish in north Louisiana was used extensively as a surface course for local parish roads. Stabilization of these roads with Type I portland cement followed by an overlay of asphaltic concrete resulted in heaving. A study was undertaken to investigate the cause or causes of the expansion as well as to identify an alternate means of stabilization. Specimens of representative soil from the affected area were stabilized in the laboratory using various cementitious materials and were cured using a variety of methods. The mix contained 5% to 20% cementitious material. The cementitious materials were Type I portland cement, lime, and supplementary cementing materials such as granulated blast furnace slag (BFS), Class C fly ash (CFA), silica fume, and an amorphous silica (AS). The unconfined compressive strength of the stabilized soil was determined. The effect of size fractions other than the gravel on the expansion was assessed, and the expansion of the specimens over time was monitored. The cement and BFS mixtures almost doubled the compressive strength of the specimens compared with portland cement alone. The finer size fractions were responsible for expansion. The magnitude of expansion was directly proportional to the amount of Type I portland cement, the amount of available moisture, and the curing temperature. Replacement of a part of the portland cement by BFS significantly reduced the amount of expansion even at the highest moisture content. No expansion was detected when CFA and AS partially replaced the cement.

Influence of High-Temperature Curing on the Properties of the Concrete Containing Ground Iron and Steel Slag

2014 ◽  
Vol 507 ◽  
pp. 337-342
Author(s):  
Meng Yuan Li ◽  
Jin Hu
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Steel Slag ◽  
Curing Temperature ◽  
Early Age ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Iron And Steel ◽  
Negative Effect ◽  
Curing Condition

The influence of high-temperature curing on the compressive strength and chloride permeability of the concrete containing ground iron and steel slag (GISS) was investigated. Under standard curing condition (20°C), the early-age compressive strength of the concrete with GISS is much lower than that of the pure cement concrete. The activity of GISS is more sensitive to the increase of curing temperature than that of cement. The increase amplitude of early-age strength of the concrete with GISS is much greater than that of the pure cement concrete by increasing curing temperature. Increasing curing temperature tends to decease the late-age strength and enhance the late-age permeability of concrete. The negative effect of increasing curing temperature on the late-age properties of the concrete with GISS is smaller than that of the pure cement concrete.

Sign in / Sign up

Export Citation Format

Share Document